Everything changes in a moment
by AllieCam
Summary: Castle calls by the 12th and sees something unexpected. It changes everything. Spoilers for everything up to 4x17. Please R&R.
1. Chapter 1

Disclaimer: none of the characters belong to me and the show doesn't either.

Hi everybody, this is the first story I have written and published for almost 5 years. It's also my first Castle fic. It's been a long time but I recently realised how much I miss writing and remembered how great the community is. I have two stories (House, NCIS) that need finishing and I'm hoping to get around to doing that but in the meantime I thought I might try something new.

Any errors are my own and are due to my being so rusty. I would really appreciate any feedback that would help me to improve.

This could be a one-shot but I have a few chapters written in my head!

I hope you enjoy it.

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><p>The change had been almost imperceptible; so tiny that he almost hadn't noticed. But it was there alright.<p>

There was a little bit more of a spring in her step. She was checking her phone more. She was just a tiny bit more eager to head home at the end of the day, instead of hanging around the precinct spending time on paperwork or old cases.

When Castle had called by the Twelfth unannounced one evening to surprise her with tickets to a _Naked Gun _marathon down at a nearby movie theatre, everything fell into place.

She was standing by her desk seemingly getting ready to go home for the night, and she wasn't alone. As she packed up her purse, she was laughing with a man who Castle had never seen before. He was about a head taller than the cop, with mid-brown hair and eyes that crinkled up at the corners as he smiled at whatever it was Beckett was saying to him. His black suit and confidence in the cops' den suggested that he was in law enforcement himself.

They weren't touching, weren't even standing that close, and to all the world could have looked like colleagues sharing a friendly joke together. But when the man reached for the coat on the back of the young cop's chair and held it up so that she could slide her arms into it, Beckett didn't bat an eyelid and allowed him to help her. As the man settled the coat around her shoulders, he gave them a light squeeze and his hands moved to gently move her long hair out from under the collar where it had been caught.

Throughout they had kept up their chatter as if it were the most natural thing in the world for him to be touching her and helping her to get into her coat at the end of the day. When Beckett turned back to face him the man's fingers just barely brushed her cheek and the smile she sent him was relaxed and easy.

Castle stood stock still. It was not the type of interaction that he and Beckett would have. When he touched her there was always a pause while they both felt the heat sizzling between them. That pause said it all really: it was that moment of awkwardness that comes when two people who have been considering going to bed together, but spend most of their time in each other's company ignoring their attraction, are jolted into remembering their desire with physical contact. It was not the type of acknowledgement that happened between people who had already slept together, and it was certainly not the type of easy touch that was evident between two people that were regularly sleeping together.

What Castle had just witnessed was the type of addition that he might make to a scene between his characters Nikki Heat and Rook, just to show his readers how they felt about each other.

Kate Beckett had a new boyfriend that she had apparently been keeping a secret. And standing in the corridor looking through the glass of the bullpen walls, Castle felt once again like an outsider looking in.

All of her talk about not being able to have the relationship she wanted until she could bring her mother's killer to justice and finally send those walls around her heart crashing down had caused Castle to hope. When she had turned up at his book signing he had been furious and hurt after three long months of silence. He had been prepared to ignore her but she had pleaded with her eyes for him to listen, and foolishly he had. In the months that followed he had been doing what he thought she had been asking him to: waiting. He had been waiting for her to give him a sign that she was ready to move on. He had assumed the she had been waiting too and little things like her obvious jealousy when his former muse had shown up out of the blue had allowed him to continue being patient. So it was like a knife to the stomach to see her so relaxed and happy with another man.

The Castle of a few years, even a few months, ago would have strolled over and introduced himself. He would have subtly made it known that this other guy was an interloper because Beckett was just marking time with some guy she didn't care all that much about before she was ready to give herself over to serious, one-and-done relationship with _him_.

Now he just quietly turned on his heel and slipped away to the elevator before he could be seen by either of them. He entered, pushed the button for the ground floor, and unheedingly watched the elevator doors slide closed. He pinched the bridge of his nose and suddenly found it remarkable that five minutes ago he had had such a spring in his step, and now he felt almost unbearably tired.

When he climbed into his car and turned the key in the ignition his only thought was to get out of the parking lot before Beckett came down to get into her car. He had no desire to see the two of them together again and he was keen to avoid being spotted by her. He didn't think that he would be able to make it through a polite conversation with her new lover. In all likelihood he would just stand there staring at her as she made the necessary introductions; watching her as she watched him for any signs that he would make the encounter awkward for her new man.

As he drove the familiar route home he thought about all the time he had spent following her around. He had never made a secret of his attraction to her and as deeper romantic feelings had developed, he hadn't really struggled to keep them hidden either. When many of the people they had encountered on cases had met the two of them, they had assumed that he and Beckett were a couple. He himself had thought that it was just a matter of time; even going so far as to say to one individual when he had enquired if they were together, "Not yet".

It must have been agonising for someone as private as Beckett to have him following her around like a lovesick puppy, he thought. Sure she had allowed him to become her friend and flirted and laughed with him, but she had made it clear early on that she was not about to have a romantic relationship with him. He had assumed that he would wear her down; that several dedications, numerous attempts at saving her life, and a multitude of 'moments' later she would at last openly acknowledge their attraction and fall into his arms.

He felt foolish. He had laid his heart out for her and for everyone else to see, but he had failed to see that it wasn't the other guys that she was marking time with, it was him. She had kept him close but never allowed him to get too close. He had been the stand-in until something better came along.

He was embarrassed and he had no one to blame but himself.

By the time he pulled in to the parking garage of his apartment block, Richard Castle had decided he was done.

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><p>AN: thanks for reading (if you made it this far!). Please leave me a comment and let me know how I did after all this time, and if I should continue. Thanks again and good luck with your writing endeavours!<p> 


	2. Chapter 2

Disclaimer: if they were mine, I would not be playing with them on paper but on screen!

I want to thank everyone who left me those kind words of encouragement and asked me to continue the story. I was really nervous to get back writing again and I really appreciate the fact that you guys took the time to let me know that I did ok with the last chapter.

I hope you all like this one. Please let me know what you think could be improved. And I apologise in advance for the section on Nikki Heat and Rook – I haven't read the books so I'm afraid I just know little bits of the plot from the show.

Enjoy!

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><p>His mother and Alexis were away for the weekend, so he was able to enter his apartment without fear of being accosted by teenage girls or some damned acting class of his mother's. He loved them both dearly but he didn't want to have to explain why he was currently sitting in a dark study, illuminated only by the light from his laptop, his hand curled around a generous glass of scotch.<p>

It was cliché, he knew, but with nobody around to witness it he felt safe indulging his impulse to take the edge off. The gnawing feeling in the pit of his stomach didn't seem quite so bad after he had gulped down some of the amber liquid, and if he didn't think about what Beckett might be doing with her lover at this very minute he could almost imagine that he hadn't left his office an hour ago to tempt her with an impromptu trip to the movies. He could almost imagine that the scene he had witnessed had been fabricated by his perverse imagination as another form of torture where Beckett was concerned.

Almost, but not quite.

His fantasies were usually brought on by something as simple as the smell of her or the feel of her. What would be to most people a tiny and insignificant event would, for Richard Castle, conjure up imaginings of how soft her lips would be when he kissed her for the third time; how the moan in the back of her throat would sound as his tongue trailed the length of her neck and came to settle between the deep valley of her breasts; how she would look into his eyes as she climbed on top of him and arched her body in ecstasy.

The torture came when reality intruded and reminded him that, whatever he might have felt, the only times he had kissed her had been to fool some hired muscle who was guarding a building where Detectives Ryan and Esposito were being held hostage; and she had shown no apparent desire to repeat the experience. Reality interrupting sweet fantasies was painful enough without also imagining her with some other man.

No, that had definitely been real. And he had the unused tickets in his coat pocket to prove it.

His laptop seemed to stare at him reproachfully. It was true that he was once again behind on his deadlines with his publisher, his ex-wife Gina. After the way that things had ended between them he highly doubted that she would be willing to be patient for this new book. She was far more likely to use this latest delay to make some point about how he was running around pretending to be a cop when he should be writing.

She wasn't wrong. Some of his writer friends had already commented that releasing one book a year was unusual for him, and teased him for losing focus. He had long been aware that his volunteering at the station had been consuming most of his time; and while it had started out as an attempt to gain some insight into world of cops – and one cop in particular – more than four years on he had been forced to admit that it hadn't been about his books for a long time.

He had been using his position as a consultant for the twelfth precinct to spend time with Kate. He'd fooled himself into believing that if he hung around long enough she would one day wake up and realise that the guy who wanted to be her one-and-done had been standing right beside her for years.

It had taken tonight for him to realise that it was never going to happen and that for the sake of his pride and his mental health he needed to move on from Kate Beckett.

His fingers rapidly clacked the keyboard.

_Nikki stared at Rook uncomprehendingly._

'_You're going?' her voice was little more than a whisper._

_He moved towards her slowly, the anger dying out of his eyes._

'_I'm so sorry, Nikki,' his tone was soft, with no trace of the roughness that had been in his voice only moments before, 'I didn't mean to tell you like that – to blurt it out in the middle of a fight.' The journalist paused to gather himself before continuing, 'I've been offered a once-in-a-lifetime assignment. I'm going to be travelling the world. I've been thinking about it for a while now, and I've realised that I have to take it.'_

_She still had that same blank look on her face but she swallowed and made an effort to get the word out: 'Why?'_

_He ran a hand through his hair in frustration._

'_Don't pretend like you don't know why, Nikki,' the hard edge was back in his voice, 'We've been at each other's throats for weeks and I can't do this anymore.'_

_Her arms came up from her sides to cross over her chest as if to protect her from his harsh words; but even as she shielded herself, she turned to face him head on and her eyes began to blaze again in her now pale face._

'_You're leaving your home to travel the world because of a few fights?' The scorn in her voice made him clench his jaw in an effort to keep from saying something he might regret._

_His pause to gather himself before replying was barely perceptible but she noticed it and felt a little jolt of satisfaction because she had been able to get under his skin._

'_It's not about a few fights, Nikki, and you know it. I just can't deal with being constantly in limbo with you! I need to know where I stand,' his tone was angry but controlled. _

'_I'm your friend. I'm your partner. I'm occasionally your lover. We sleep together but we never talk about it,' his voice was getting louder, 'We almost freeze to death in each other's arms and we never talk about it! So, no, I don't know what we are to –_

Castle suddenly stopped typing and looked down at the screen.

The near death experience in the freezer hadn't been between Nikki and Rook but between him and Beckett.

He sighed and slowly tapped the backspace key until the offending words were deleted.

Time to try again.

''_It's not about a few fights, Nikki, and you know it. I just can't deal with being constantly in limbo with you! I need to know where I stand,' his tone was angry but controlled. _

'_You need to figure out just what it is that you want,' he took a breath and stepped towards her, willing himself to continue, 'And if it's not me, I can accept it. But I need to know, Nikki, because you can't keep playing with me.'_

_Nikki felt pinned by that earnest gaze. She couldn't move. She couldn't breathe. And she couldn't speak._

'_You need to tell me what you want,' his voice was low and he was still moving towards her, 'Because I don't think you have a damn clue.'_

_For once in her life she felt like a rabbit caught in the headlights. 'I – I,' she stammered but she couldn't get any further, the words were caught in her throat. _

_He was right in front of her now, so close that all she had to do was lean forwards and capture his lips with her own. _

_She didn't move._

_He gave a little sigh and bent down to brush his lips softly against her cheek. She closed her eyes as she took in the feel of his soft lips and bristly five-o'clock-shadow on her skin; it was over so quickly that she could have been forgiven for thinking that she had imagined his touch._

_One moment he was standing in her darkened hall softly telling her goodbye, and the next he was gone._

Rick Castle carefully read back over his last few lines and let out a sigh of his own. If only it were as simple as escaping for a trip around the world for him. But he couldn't just leave the precinct. He had made friends there – Ryan, Esposito and Lanie – and just because he was hurting it didn't mean that he should hurt them too by taking off without a word.

Then there was Kate. She was his friend too. No matter how much he was hurting right now, he had to hold on to the fact that they did care for each other; maybe she didn't care for him in the way that he wanted her to but she had stood by him and saved his life time and again. He couldn't just throw that away because he had been foolish enough to fall in love with her and delude himself to thinking that she was on her way to feeling the same way about him. He was angry with her and he was hurt, but even with those feelings he couldn't imagine cutting her out of his life forever.

He was also painfully aware that even had he wanted to do so, he would not have been able to quit the precinct without putting Kate's life in danger. The mysterious man who had made that deal with him about keeping Kate away from her mother's murder case had made it clear that if he wasn't around to stop Kate from investigating, then all bets were off as far as Beckett's safety was concerned. His mind briefly flashed to Montgomery's funeral and he gave a faint involuntary shudder at the thought of being responsible for Kate being shot again.

His fingers groped for his glass on the desk and he raised it to his lips just as his phone began to ring.

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><p>AN: please R&amp;R. I really appreciate any feedback - good or bad! And thanks for making it this far!<p> 


	3. Chapter 3

AN: Can I just say that I am really disappointed in the last episode? Castle is great but seriously, how long are they going to keep the 'will they, won't they' thing going? I love the two characters but there are only so many obstacles that they can put in their way before the audience is going to get frustrated and turn off. They did it with Grissom and Sarah in CSI and honestly I felt so cheated that after so many seasons they didn't even give the audience the satisfaction of seeing how they got together. I am hoping that this doesn't happen here. And after the lack of confrontation in the last episode, I think we are due one hell of a finale!

As ever, the characters do not belong to me – if they did, the last episode (and perhaps the last season) would have been a lot different!

Thanks to those of you who reviewed my last chapter – I really appreciate your input. This is my first real attempt at smut so it would be great to hear from you guys how it goes. As ever, please R&R – it's the only way I'm going to get better!

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><p>"Hey, Espo!"<p>

Detective Havier Esposito turned to greet his partner, Kevin Ryan, who was picking his way carefully around the debris of the construction site. Ryan made his way to where the other detective was kneeling beside the body. The victim's clothes suggested that this was the body of a young man, but even at a glance it was clear that there would be issues with identification.

Ryan stopped short as he caught sight of the gruesome tableau laid out before him.

"Jesus!" he exclaimed before he could stop himself.

Esposito got to his feet, nodding as he did so. "I know, man."

There was a long pause as they surveyed the body in silence. The man's face had been smashed, probably with a piece of rubble that had been to hand in the construction site. His finger tips had been removed also probably with a box-cutter, the medical examiner said, and a brief examination of what was left of his face indicated that his teeth had been removed.

"Somebody sure didn't want this guy to be identified," Lanie's voice cut into the partners' reverie. She gave a sigh, "I'll get him back to lab and we'll see what we can do, but unless his DNA is in the system it's going to be a struggle to give you guys anything to go on. I'll do my best, though."

"Thanks, Lanie," Ryan said with a grateful smile. Lanie was the best medical examiner in the city and if she said she would do her best then their victim was in good hands.

"Can I take him now or are you guys still processing the scene?"

"We were gonna wait for Beckett but I haven't been able to get through," Esposito responded, "She's not answering at home and I've tried her on her cell a couple of times."

"What about Castle?" The doctor inquired.

Esposito shrugged. "Beckett usually calls him."

"Well, maybe he'll know where she is," she gave another glance at the body, "And it might be an idea to call him in anyway. This might be just the kind of case that you guys could use one of his crazy ideas on."

Esposito nodded. "I'll try Castle and see if I can get through to Beckett this time. So, hold off on removing our victim for a bit. Beckett won't like it if she doesn't get to see the crime scene."

Lanie nodded. "Sure, but we're gonna have to make a move soon. There's rain forecast and if we don't move him soon we could be looking at something worse than a pissed off Kate Beckett – compromised evidence."

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><p>Castle's fingers groped for the glass on his study desk and he raised it to his lips just as his cell began to ring. He hesitated only for a second and then instinct kicked in. He grabbed his cell and checked the caller ID. <em>Esposito, <em>it read.

Normally the calls about a case came from Beckett. That Esposito was calling him so late at night was unusual enough to pique his interest.

"Castle," his greeting had none of the humour that he usually reserved for Kate Beckett and he reached again for his glass of scotch.

"Hey, Castle," the detective at the other end of the line responded, "Have you seen Beckett today?"

The author had been in the process of taking a mouthful of the amber liquid and this non-sequitur threw him off balance.

Esposito heard spluttering and coughing.

"Are you ok, man?"

Rick coughed again and took a breath to steady himself. "Fine. Fine. Sorry, I was just taking a drink – it went down the wrong way," he explained somewhat unnecessarily.

"So, have you seen Beckett today?"

"Me? No – no," Castle was guiltily stumbling over his words, "I haven't seen anyone today. I've been home writing all day. I'm writing now – why do you want to know?"

As he waited for the cops reply he resisted the urge to start banging his head against the wooden surface of his desk. He'd always been a terrible liar. And why was Esposito calling him? Had he been seen at the precinct? Had Kate seen him leaving the parking lot? Was she wondering why he had high-tailed it out of there without speaking to her?

Esposito broke in to his guilty thoughts. "We have a case. I've tried her at home and she hasn't answered. And she's not answering her cell either. We thought you might have seen her and we thought we could use your help on this case too."

There was silence at the other end of the line.

The cop took the lack of response for acquiescence: "The address is the construction site downtown at thirty-first and –"

Castle cut him off. "Sorry, Esposito, I'm writing tonight. I'm sort of on a roll and I've got a deadline coming up so I'm not gonna make it tonight."

There was something a little funny about his tone.

At the construction site, the cop frowned. "Sure, Castle, maybe we'll see you tomorrow."

The author murmured something non-committal.

"And if you see Beckett, maybe tell her to give me a call?"

"Of course."

Castle rang off.

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><p>Ryan approached his partner.<p>

"Is he on his way?"

Esposito shook his head. "He said he's writing tonight."

The words felt foreign. In all the time they had known Castle he had never turned down a case to work on a book. If anything, he was usually dodging his publisher's phone calls at the precinct rather than taking time away to work at what was supposed to be his full-time job.

Ryan grinned in disbelief. "Maybe he got a better offer."

Something suddenly struck Esposito. "You know, he did sound very guilty when I asked him if he had seen Beckett today…"

The Irishman's eyes widened. "You don't think…?" He didn't even know how to finish that sentence.

Esposito shrugged. "I've no idea, but it wouldn't be all that surprising, would it? Those two have been dancing around each other for years." A grin spread across his face. "Let's ring Beckett and see if she picks up."

The smile on Ryan's face matched his partner's. "And if she does, let's see if she gives an excuse…"

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><p>Across town, Rick Castle had carefully laid his cell down on the desk.<p>

Detective Kate Beckett was uncharacteristically failing to answer her phone.

Kate Beckett wasn't picking up her cell.

Kate Beckett was unavailable.

Kate was with_ him._

He was scarcely away of his body rising up out of his chair, of his fingers curling around the now empty glass, of his arm swinging away from his body, of the glass sailing through the air.

But when the glass crashed into the thick wooden door of his office and shattered he heard it.

And he felt it.

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><p>In another apartment on the other side of town, Detective Kate Beckett was being pinned against a wall by Detective Martin Frost from the Ninth Precinct.<p>

"You taste incredible," he mumbled into her mouth.

She smiled in response, "You're only saying that because we skipped dinner."

It was true. They'd had a reservation and everything but when he had shown up at the precinct to collect her they'd made a mutual decision to go straight for dessert back at his place. As soon as they'd entered they apartment, they'd pretty much jumped each other. There had been a flurry of kisses and rapid movements of hands trying to get rid of clothes that were in the way.

When she was down to her bra, with her attention focused on making short work of the buttons of his shirt, he had used the opportunity to pin her against the wall with her hands above her head.

Kate Beckett was one tough cop and if she had wanted to get him off her, she would have but she was enjoying the feel of his lips sliding down her neck and making their way towards her breasts even as his free hand fumbled at the zipper of her pants.

They'd been sleeping together for a few weeks now and he always managed to surprise her in the bedroom.

They'd met at his precinct a month before when she had called by to visit an old friend. The attraction between them had been instantaneous and uncomplicated. Martin Frost was a nice guy, a fun guy but Kate Beckett was under no illusions – he was not the type of guy she was going to fall for.

She gasped as his fingers finally found their way into her pants and were brushing insistently between her legs through her silken panties. However, when he did _that _she could almost change her mind about him. Before Martin there had been a long gap in her sexual history.

Her hands broke free from where he had been holding him. One moved to hold him in place she arched into his touch, and the other began working his belt.

Just as she reached into his boxers her cell began to ring. It was the ringtone that she had set for all things work-related.

Martin sighed and pulled away, his eyes filled with amusement and frustration.

"I guess it was too much to hope that we might both be able to escape from work for a full night."

He started to pull his hand out from between her legs but her fingers curled around his wrist.

"You stop doing that and I'll shoot you," she sounded serious.

He grinned and pushed her panties aside so that he could start working her clitoris without anything in the way.

She moaned into his mouth and then started to run her fingers slowly up and down his shaft to even the playing field. The groan and jerk of his hips that this elicited was gratifying.

Her cell rang again.

"Could be important," he mumbled between kisses, "You should probably pick up." He didn't sound very convinced however, and he certainly hadn't attempted to stop what they were doing.

Kate wrestled with her conscience for a moment and then she shook her head. "Quickie first, then I'll call them back."

Martin Frost grinned as he allowed himself to be dragged towards his bedroom, "Yes, ma'am."

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><p>It was only forty minutes later when Beckett got to the crime scene.<p>

Even if her more mussed up than usual hair and slightly rosy cheeks hadn't been a dead giveaway to her colleagues, the spring in her step and the secret smile that was impossible to hide completely proclaimed exactly what she had been up to that evening.

"Esposito. Ryan," she greeted them enthusiastically, "Sorry I'm late."

"You didn't bring Castle with you?" Ryan inquired innocently, both men carefully watching her reaction.

At the mention of his name she felt a little mental start. She suddenly realized that she hadn't thought of him at all when she had been Martin. Her cheeks coloured slightly at the realization, something that didn't go unnoticed by the other two cops, and she felt angry at herself for the guilt that suddenly came over her.

"I haven't seen Castle all day," she said shortly, "Isn't he here?"

"He said he was writing tonight," Esposito replied, watching her closely.

Well, thank heaven for that, she thought.

"Fine, he can catch up tomorrow," she said and then abruptly moved the conversation away from the mystery writer with a jerk of her head in the direction of the corpse, "What have we got?"

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><p>AN: Please review and let me know what you think. I apologise for taking so long to post but things at work and college are crazy right now. I realize that for most people, this chapter will not be their cup oftea. Rest assured that this <em>is <em>as Caskett fic and that it is centred around my favourite should-be couple. However, this is the fic that I have in my head! Please R&R and tell me what you liked/hated!


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